Drill head safety mechanism



Sept. 29, 1931. w. c. DE ROO 4 I DRILL HEAD SAFETY MECHANI SM Filed Jan. 4, 1930 2 Sheets-Sheet l ,jwwntoz 129 l i I VN/z'am CZDe/Yao Sept. 29, 1931. w. c. DE R00 3 0 DRILL HEAD SAFETY MECHANISM Filed Jan. 4, 1930 2 Sheets-Sheet 2 k /////////////////fl///////////// ///////LA gwuento'o WN/z'a in CD2 R00 Patented Sept. 29; 1931 WILLIAM 0.121: 300, or CINCINNA I, oHIo, AssIGnoR TO THE rosnroxmnofiinn COMPANY, or omcmna'rn-onmn con-ronarionor -on1o.

DRILL HEAD sArntrY MECHANISM Application ,filed January 4, 1930. Serial Nor 418,530.

This invention relates to a safety interlock for drill presses and the like and hasfor an objectthe provision of a simple means whereby the feed of a drill spindle is held out of 5 engagement when the spindle is retained against descent by a spindle safety-catch."

Another object is to'provide anarrange ment for the purpose stated thatjwillpermit of the completion of a power feed operation 10 of the spindle even though themaehinedoecomes. unsafe for subsequent operations the actuation of thespindlesafety catch being deferred until the given operation is completed and then being permitted'to come into 18 operation to prevent the falling of the drill spindle when thelatter is released fromithe sustaining influence Tof-the power feed mechacuism. Another object of the invention is the pro- 80 vision of a. simple extension upon "a member of the mechanism whereby automatic upper and lower limit power feed-throw-outis accomplishe'd without'the need of comple'x ad.-

ditional mechanism.

L 25 The arrangement of'the' device of this in- 'vention is such that a spindle safety catch and spring counterbalance means as shown'in. a patent of 1V. C. De Roo No.1;756A54, maybe employed in its entirety; The structure of 28 the present invention requires buta few relatively simple means whereby the foregolng objects are attained with certaintyand without danger of'i'failure'because of inadvertence on the part of the operator.

These and other objects areattained by 'the means described herein, and disclosed in the accompanying drawings, in which I Fig. 1 is a fragmental front elevational view of a drillfpress head embodying the pres-,

ent invention, parts being broken away.

Fig. Q'isa view taken on line 2--2 of Fig. 1. The drill head, spindle and the spring counterbalance and spindle clutch employed 1 in this invention and fully explained in the De I 4. R00 patent above referred to comprises a head casing 4 supportinga spindle structure'5 pro.- vided with the usual rackteeth 6' and adapted to be held and reciprocated through the agencyof a gear 7 whichmay be both manual- 9,1y andpo-Weractuatedh 1 The gear 7 is secured on shaft Sand is also connected w1th a gear train comprising gears 9, 10 and llmounted upon a plate or bracket .12. i A shaft 13 has the gear 11 secured thereto and is journalled at the rear of the casing head. This shaft 13 is also j ournalled in a hollow 1 drum 14 which is normally held against rotation by the engagement of worm teeth'1'5on' thedrum meshing with the worm 16 on a transverse rod 17 I A counter-balance spring 18 fashioned likea clock spring has its one endsecured to'the shaft 18 and its other end secured, as'bya. screw 19* to the interior face of the bodyof the drum; When. the

gear and its connected train is'actuated in one direction it will lower the spindle and the trainwillrotate the'shaft 13 and thus wind up or place the spring 18 under tension and oppose the tendency to drop by gravity. When the gears are actuated in-the opposite direction the spindle is lowered and the spring is loosened; to a corresponding degree. Adjustment of the tension of'spring 18 may be made by turning the handle 20 fixed to the well? so'that the worm 16 is rotated. In

this way an accurate counterbalance of the spindle is attainable under all conditions and, so longas the'springis effective, thespindle may be manipulated with ease. f l

The spindle safety catch which is adapted 1 to become operative in the eventthespring 18 'shouldbreak, is provided by-fixing a col= lar 21 upon the rod 17 and mounting a spring TOOL 22 upon the "rod'und'er compression with one 7 end abutting tliecollar and the other end abutting the interior face of the housing or. a fixed journal member QQO-mounted therein. 111 this way "the rod is constantly *urged toward the right in Fig. 1 andtheipower of 'spring 22 opposesthe' tendencyof spring 18 to shift the rod to theleft. Adjacent its opposite end the rod 17 has an annular groove '23. A short bar 24 is pivoted intermediate its ends upon suitableistud 25 and :carries uponits one end-1a yoke, 26 disposed'in the annular-groove23 of rod l7.., At its oppo site end the bar 24 has a ball and socket con nection 27 withthe lower endof a safety catch member 28 which is pivoted as at 29 upon; a suitable extension-8O of the plate,12..

Inn

sistance; The descent of the spindle is'thus effectively arrestedthrough the gear train which is locked by the tooth 31 engaging gear 10. The foregoing structure is essentially that embraced the De R00 Patent No. 1,7 56,454 and is most effective when a friction clutch mechanismiis used for the power feed.

In addition to this structure the present invention comprises means cooperating with the safety catch means to positively control the power feed clutch so that failure of the counter-balance 18 will not interrupt a power feed operation which is under way, but will nevertheless release the safety catch for effectively holding the spindle after the power operation is complete and the clutch is thrown out. Once. the clutch is thrown out and the safety catch operative, the same means of the invention precludes subsequent actuation of the clutch. untilthe counterbalancespring has been repaired.-

Furthermore, by a providing a gear 10 (which makes one complete revolution within the limits of reciprocation of the spindle) with pa lug and by providing an extension finger on the structure of the invention, an automatic upper and lower power feed stop is effected. This entire arrangement'makes the mechanism entirely fool-proof. The various safety features each operate under the desired condition without interference one with the other. i

The invention is carried out in the present embodiment by providing on the casing 4 a pair of rigid vertically aligned lugs 32 and 33 having bores therein to receive a pivot pin 34 upon which the clutch trip fork member of the invention is pivoted. This member is somewhat in the nature of a bell crank lever and can be made from a single casting if desired. Bypreference however andin order to effect accurate ad justment thereof the device is formed of a lower trip fork member 35 pivoted on pin 34 and having a clutch-throw yoke 36 at the end thereof operating in an annular groove 37 of a clutch spool38. In this way the member 35 is rocked on. its pivot each time the clutch is actuated. An integral arm' 39 substantially overhangs the lower trip fork member and has a'flat top face. Adjacent the free end of the arm 39 is a vertical threaded bore 40. I he upper trip fork member 41 is also pivoted on the-pin 34 and has its bottom face resting on the top face .close proximitywith the'faoe of gear 10.

The gear 10 has a boss 47 on the face which moves in a circumference and effects a dis-' placement of the tip 46 sufficient to turn the trip fork mechanism on its pivotal mounting at 34 for throwing out the power feed clutch. As previously explained this arrangement serves as a limit stop for the power feed of the device.- 'When the clutch is thrown out the yoke 36 is moved and effects movement of the trip fork'about its pivotal mounting so as towithdraw the tip 46 from it's position and also to remove the block 45 from the path of the collar 21 on rod 17 Thus if the counter-balance'spring 18 should break while thes pindle is under power feed, the block 45 would preclude shifting of the rod '17 so that the bar 24 could not operate to throw the safety catch 28 with itsrtooth 31 into the L path of gear 10. During the power feed the drill spindle is suspended and" under good control by the gearing. It might be dangerous'under such circumstances to throw the safety catch tooth 31 into the path of gear '10. Thus the power fed drilling operation may be continued until'the operator throws out the clutch, or should he fail to do so the power feed would continue until the boss 47 operating on the tip 46 of finger 44 would effect shifting of the trip fork and thus automatically throw out the clutch. As soon as the clutch is thrown out either manually or automatically, the block 45 is removed from the path of collar 21 whereupon (since the spring counter-balance 18 is assumed to have been broken) the compression spring 21 forthwith shifts the rod 17 to the right, actuates pivot bar 24 and throws safety catch 28 to the left so that the tooth 31 effectively locks the gear 10 and thus arrests descent of the spindle. Should an operator attempt to again throw in the power feed clutch he would find that movement of the clutch spool was effectively blocked because the collar 21 would preclude movement of the block 45. In this way it is made impossible'to subject the gear trainto power after the safety catch has functioned.

The clutch 48' (not detailed) may be of any type and preferably has worm teeth 49 formed on the periphery of one of the members for receiving power through a worm 50 on a controlled-power actuated shaft 51. The clutch is manually actuated by any suitable means such as handle levers 52 which control 7 the setting and release of the'clutch,

What is claimed is:

1. In a machine tool the combination of a safety catch, a gear adapted to be arrested by engagement of the catch therewith, a longitudinally movable rod normally urged to set the catch, normally operative means in said machine tool resisting movement of the rod, a power control clutch, a trip lever for operating the clutch and also movable by the clutch, a boss on the gear, a finger on the trip lever adapted to be displaced by said boss, a collar on the rod and a block on the finger retained thereby in the path of the collar when the clutch is in engaged position to preclude operationof the safety catch while the clutch is engaged and retractable upon disengagement of the clutch for releasing the safety catch upon failure of the normally resisting means, the boss on the gear and said finger automatically disengaging the clutch upon predetermined rotationof the gear.

2. In a safety interlock for a spindle feed clutch and a spindle safety catch the combination of a spindle, apower feed clutch, a

gear train operable upon feeding movement of the spindle, a counter-balance yieldably resisting descent of the spindle, a safety catch for locking the gear train against movement to arrest movement'of the spindle, a rod urging said catch to operative position, means on the counter-balance resisting movement of said rod and releasable upon failure of the counter-balance, a trip fork pivotally mounted for movement upon movement of the clutch, a collar on the rod and a block on the trip fork disposed in the path of the collar when the clutch-is engaged, the collar being disposed in the path of said block when the clutch is disengaged and the safety catch is operative for precluding engagement of the clutch when the gear train is locked.

In testimony whereof, I have hereunto subscribed my name this 26th day of December,

WILLIAM 0. DE ROO. 

